clearance
noun
Definitions
The act of clearing or something (such as a space) cleared
The distance between two moving objects, especially between parts of a machine
The height or width of a tunnel, bridge or other passage, or the distance between a vehicle and the walls or roof of such passage; a gap, headroom.
A permission for a vehicle to proceed, or for a person to travel.
Example: He got clearance to travel to America, even though he had previous links to terrorists